For a quick hack,
s{(http://\S+?)(\s+)}{<a href="$1">$1</a>$2} will do what you ask. The important thing to note is the
\S+?, which makes the regex non-greedy,
i.e. it'll match the minimum amount required for the regex to succeed, rather than the maximum amount, which is what
\S+ or
.* would do. I've also used
\S (any non-space character), as it's best to avoid
. where you can: see
death to dot star.